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ICDs are routinely implanted in heart failure patients with ejection fractions (EFs) of 35% and lower to prevent sudden cardiac death. However, the benefits in patients at the higher end of the spectrum-- between 30% and 35%-- have not been well demonstrated in clinical trials, since few patients in this range have been enrolled in clinical trials.

Now a new study published in JAMAsuggests that the benefits in this group are similar to the benefits in heart failure patients with more severely depressed EFs.

Sana Al-Khatib and colleagues analyzed data from the NCDR ICD registry and the GTWG-HF database and compared the mortality benefit associated with ICDs in patients with EFs between 30% sand 35% with those in patients with EFs below 30%. At followup the ICD-associated reduction in mortality was similar in both groups. At 3 years the adjusted mortality rates in the EF 30%-35% were 47.1% in the ICD patients versus 58% in the patients without ICDs. In the EF <30% group the rates were 46.1% and 57%. The hazard ratio for ICD patients with EF 30%-35% was 0.83 (CI 0.69 - 0.99, p = .04). The HR for ICD patients with EF <30% was 0.72 (CI 0.65 - 0.81, p < .001).

The authors wrote that their findings "support guidelines’ recommendations to implant a prophylactic ICD in eligible patients with an LVEF of 35% or less." Although "the difference in absolute risk by 3 years was not large (3.6% at 3 years), it was significant and close in magnitude to what was observed in the clinical trials of prophylactic ICDs."